During a person's sleep period, many crucial biological processes take place such as development of the immune defenses, cell regeneration, or memory consolidation.
A sleep deficit or poor quality sleep are therefore now recognized as sources of memory disorders and as important factors in the development or aggravation of serious diseases such as Alzheimer's, Parkinson's, hypertension, or obesity.
It has been observed that these beneficial biological mechanisms associated with sleep are associated with a specific brain activity with waves of specific frequency: the slow brain waves.
In modern societies, stress and productivity constraints lead to poor and shortened sleep, particularly for the sleep stages in which the beneficial biological mechanisms mentioned above occur. This has adverse effects in the short term (fatigue, memory, concentration) and long term (increased risk of onset of chronic diseases).
There is thus a general need to enhance the beneficial effects of a person's sleep, particularly when the duration and quality of sleep are subjected to strong external stresses.
For that purpose there are known devices for stimulating the brain, in particular during a person's deep sleep stages, which seek to promote deep sleep.
For example, document U.S. Pat. No. 8,029,431 describes a system applying non-invasive stimulation to a person's brain during a deep sleep stage. The system comprises a central processing unit receiving the signals measured by an electrode panel in order to capture an electroencephalogram of a person and control a transcranial magnetic stimulation device so as to stimulate the person's brain periodically at a predefined frequency when in deep sleep, in order to enhance deep sleep.
Such a device has disadvantages: a transcranial stimulation device is bulky and little suited for daily use since it involves a hinged stand on which is hung a coil powered by a generator. Furthermore, such a device must be properly positioned relative to the target areas of the brain, which is difficult to achieve throughout a night's sleep, especially when the person moves about in the bed, and therefore implies reliance on a robotic arm controlled by computer, further restricting the applicability of the solution to daily use. Moreover, a given periodic stimulation is not adapted for everyone due to brain wave variability from one individual to another, and the use of such a device therefore requires the presence of medical personnel trained in determining and adjusting the stimulation frequency for the user, which further complicates the adoption of such a device in daily use and its ease of use.
There is therefore a need for a device for stimulating slow brain waves that is easy to use, accessible to non-medically trained personnel, and compact and comfortable so that it can be used in an everyday context, which significantly enhances the beneficial effects of a person's sleep, which improves where appropriate the stability and duration of sleep stages, which is easily adaptable to the user so that it can be used by a variety of people without complex modifications, and which is simple and inexpensive to manufacture so as to guarantee its accessibility to the general public.